Analog to digital conversions of vocalizations of rats, the F2 of a 6-way cross of wild and domestic strains of rats (Rattus norvegicus), were precisely associated with behavior related to the vocalization. The vocalization data base consists of thirty 45-minute samples for each of two populations of 40 rats each. Dictated observations, concurrent with recording of vocalizations, provided details of individual and inter-individual behavior. On the average there was one such detailed statement about behavior during each 15 seconds of vocalization recording. The present analysis of these data is providing insights into (a) crowding induced changes in vocalizations in contrast to (b) changes in vocalizations characterizing rats which have learned cooperative behaviors.